1. Field of the Invention
The present invention relates to a solid oxide electrolyte fuel cell (SOFC), and more particularly to an SOFC available, besides for power generating purpose, as an electrolyte cell of hydro-electrolysis, CO-electrolysis or the like.
2. Description of the Prior Art
As an SOFC in the prior art, a construction proposed by the applicant of this application and disclosed in Laid-Open Japanese Utility Model Specification No. 4-8259 (1992), has been known. FIG. 3 in the accompanying drawings of the present application is equivalent to FIG. 1 in this laid-open U.M. specification, which shows an outline of the proposed construction.
In FIG. 3, reference numeral 1 designates a generating layer composed of a solid oxide layer 2 and a fuel electrode 3 and an oxygen electrode 4 respectively disposed on the opposite sides of the solid oxide layer 2. Above and under the generating layer 1 are disposed laminated layers 8a and 8b each consisting of an interconnector layer 5 and an oxygen electrode 6 and a fuel electrode 7 respectively laminated on the opposite sides of the interconnector layer 5. An outside crest portion 9 of the fuel electrode 3 on the upper side of the generating layer 1 is bonded with the fuel electrode 7 of the upper laminated layer 8a, and a fuel passage 10 is formed of a space reserved therebetween. On the other hand, an outside crest portion 11 of the oxygen electrode 4 on the under side of the generating layer 1 is bonded with the oxygen electrode 6 of the lower laminated layer 8b, and an oxidizer passage 12 is formed of a space reserved therebetween.
As explained in the above-referred laid-open Japanese U.M. specification, in contrast to the structure so far considered a main current, the above-described structure is a really important proposal in this technical field in that members not directly concerned in power generation such as support members interposed between the generating layer 1 and the laminated layers 8a and 8b are made unnecessary.
It is to be noted that while an SOFC has a power generation efficiency exceeding 60% and is ranked at an important level in view of measures for energy control, a countermeasure such as reduction of a manufacturing cost is necessitated. Although the SOFC structure in the prior art shown in FIG. 3 achieved an important improvement in this respect, it still involved a problem that the oxygen electrodes 6 and the fuel electrodes 7 forming the laminated layers 8a and 8b, which are not directly concerned in power generation per se, were necessary.
In the above-described construction, since the generating layer 1 employed a dimpled structure, electrons produced in the generating layer 1 would concentrate to a dimpled portion (recessed portion), and hence, if the dimpled portion is in itself directly bonded with the interconnector layer, an electric resistance becomes large. The reason for the necessity of the oxygen electrodes 6 and the fuel electrodes 7 forming the laminated layers 8a and 8b is because it was intended to bring the dimpled portions into contact with the corresponding electrode 6 or 7 so that the produced electrons can diffuse and a lateral flow of electrons can be generated.